Tension adjustment for stringed musical instruments

ABSTRACT

A tuning mechanism for a stringed musical instrument comprising a compound pivot assembly for anchoring the ends of the vibrating strings, said mechanism including pivoted members for balancing the tension in each string of separate pairs of strings, and other pivoted members for balancing the tension in one pair of strings with respect to tension in another pair of strings whereby a change in tension of one string will affect the tension in each of the other strings, and means for effecting a common adjustment of each of the pivoted members during a tuning operation.

United States Patent Eurich TENSION ADJUSTMENT FOR STRINGED MUSICAL INSTRUMENTS [72] Inventor: Robert C. Enrich, 3109 Delaware, Fling, Mich. 48500 [22] Filed: May 4, 1970- [21] Appl. No.: 34,205

[52] US. Cl. ..84/312 51] Int. Cl. ..Gl0d 3/14 [58] Field of Search ..84/267, 297, 312, 313

[56] References Cited UNITED STATES PATENTS r 2,897,711 8/1959 Matthew et a1 ..84/313 3,174,381 3/1965 Matthew et al ..84/313 Ryan .:...84/3l2 Oct. 3, 1972 Primary Examiner-Richard B. Wilkinson Assistant Examiner-Lawrence R. Franklin Attorney-Donnelly, Mentag & Harrington [57] ABSTRACT A tuning mechanism for a stringed musical instrument comprising a compound pivot assembly for anchoring the ends of the vibrating strings, said mechanism including pivoted members for balancing the tension in each string of separate pairs of strings, and other pivoted members for balancing the tension in one pair of strings with respect to tension in another pair of strings wherebya change in tension of one string will affect the tension in each of the other strings, and means for effecting a common adjustment of each of the pivoted members during a tuning operation.

12 Claims, 12 Drawing Figures PATENTEMBN 1972 SHEET 2 [IF 3 Y INVENTOR: BY Faber? C [and I lxlll :5 l4 mm g uw w Wm mm QB ATTO PNEYS PATENTEnuma m2 3695137 SHEET 3 OF 3 INVENTOR:

BY Poker! 6 [uric/1 AT'TOPNE Y5 adi .k

GENERAL DESCRIPTION OF THE INVENTION My invention is related to the disclosure of my copending application Ser. No. 80l,489,filed Feb. 24, 1969. It comprises improvements in an adjusting mechanism for tuning a stringed instrument such as a guitar, but the principles of my invention may be applied as well to several other stringed instruments. For purposes of this disclosure I have described and illustrated a guitar, although I do not intend that the scope of my invention should be restricted to this embodiment.

The tones of the vibrating strings of a conventional stringed musical instrument are adjusted by controlling the tension in each of the individual strings. In the case of a guitar this is achieved by string adjusting pegs located on the neck of the instrument. A tuning board carried by the neck accommodates the string adjusting pegs.

The desired individual string tension is obtained by adjusting each peg and comparing the tome of one string with the tone of the other after appropriate adjustments of the other pegs. This is a time consuming and tedious job which can be done properly only by a skilled artist.

It is usual for such a musical instrument, after being adjusted in this way, to become out of tune if the ambient temperature should change or if the strings themselves should be strained due to usage.

It is an object of my invention to overcome problems associated with tuning musical instruments of this type by providing an automatic tension adjusting feature which will establish the desired relationship between the tension of one string with respect to the tension of each of the other strings.

It is an object of my invention also to provide an adjusting mechanism of this type whereby the artist may adjust the tension in each of the strings by a simple manual adjustment that is common to each of the strings. Following this coarse adjustment, the individual pairs of strings can be fine-tuned by a further simple manual adjustment.

The tone of one string of each of the pairs of strings will remain fixed with respect to the tone of the other string in that pair after the adjustment is made. Any change in tone due to a change in temperature or to yielding of the strings can be made by a common adjustment for each of the strings.

If the gages of the strings should be changed, a simple adjustment is required for the paired strings in order to effect the required relative tensions, but this secondary adjustment remains constant. After it is made, any further adjustments can be made by using the common adjustment for all of the strings.

Each of the pairs of strings is anchored to a pivoting member. Those members, in turn, are pivoted on Separate parts of second pivoted members, which in turn are pivoted on a third pivoted member. The third pivoted member is pivoted on a stationary pivot, the position of which can be adjusted by the aforesaid coarse adjustment device. The third pivoted member also supports one of the pivoted members for still another pair of strings. The ultimate reaction point for all of the strings, then, is the stationary pivot since the first pivoted member is a reaction point on the second pivoted member, which in turn has a reaction point on the third pivoting member.

The secondary adjustment for each of the individual pairs of strings is achieved by changing the relative distances between the ends of the strings with respect to the pivot axis for their associated pivoted members.

BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWINGS FIG. 1 shows a plan view of a guitar embodying the tuning mechanism of my invention.

FIG. 2 is an enlarged plan view of the headpiece of the instrument shown in FIG. 1.

FIG. 3 is a cross sectional view taken along the plane of section line 3-3 of FIG. 2.

FIG. 4 is a side elevational view as seen from the plane of section line 4-4 of FIG. 2.

FIG. 5 is a cross sectional view as seen from the plane of section line 5-5 of FIGS.

FIG. 6 is a cross sectional view taken along the plane of section line 6--6 of FIG. 3.

FIG. 7 is a plan view of the adjusting mechanism for the instrument of FIG. 1 as seen from the plane of section line 7--7 of FIG. 8.

FIG. 8 is a cross sectional view taken along section line 8-8 of FIG. 7.

FIG. 9 is a cross sectional view taken along section line 9-9 of FIG. 8.

FIG. 10 is a partial plan view of one of the pivoting members of a pair of strings.

FIG. 11 is an isometric view of the adjusting mechanism showing the principal elements illustrated in Orthographic form in FIGS. 7 and 8.

FIG. 12 is a plan view of the adjusting mechanism showing the uppermost cover plate.

PARTICULAR DESCRIPTION OF THE INVENTION In the drawings, the numeral 10 designates generally in FIG. 1 a guitar having a body portion 12, a neck portion 14 and an anchor portion 16. A string bridge 18 is secured to the top of the body portion 12. The strings 20 are trained over the bridge 18, the latter providing a first node point for each of the strings.

The right hand end of each of the strings 20 is anchored on the string adjusting mechanism 22 which includes features of my invention. The left hand end of each of the strings 20 is anchored to the anchor member 16, which is best illustrated in FIG. 2. This anchor member comprises a bracket having a base portion 24 which is secured to the anchor portion 16 by screws 26. A flange 28 on the anchor 24 is engaged by anchor segments 30. The strings 20 pass through holes in the flange 28. One end of each string is situated between each pair of segments 30. These segments 30 are held securely in place by clamping screws 32. Segments 30 grip the ends of the strings 20 and restrain them to provide a firm anchor support.

The openings in the flange 28 are best seen in the cross sectional view of FIG. 4. They are designated by reference character 34. The openings are arranged in evenly spaced relationship along a straight line as indicated in the cross sectional view of FIG. 5.

The cross sectional view of FIG. 6 shows the ends of the strings clamped securely in place between the adjacent segments 30.

The strings are formed with a varying gage in the usual fashion. These may be the standard gages that are guitar employing the principles of my invention.

The adjusting mechanism 22 comprises a base plate 36 having a right-angle flange 38 adapted to be positioned against the edge 40 of the body portion 12. A stationary bracket 42 may be secured to the flange 38 as indicated best in FIG. 8.

The left-hand end of the base 36 can be secured to the body 12 by a wood screw 44 and the flange 38 can be secured to the edge 40 also by wood screws, although other fastening means can be used.

A slide 46 is positioned upon the base 36. Base 36 is provided with a guideway in the form of a slot 48, as best seen in FIG. 11, which runs in a direction parallel to the direction of the strings 20. Located in the slot 48 is a guide plate 50 which is secured to the underside of the slide 46, as indicated in FIG. 8. The slide 46 thus can move longitudinally with respect to the direction of the strings 20, although side shifting movement of the slide 46 is prevented.

The slide 46 includes a vertically extending wall 52 which is provided with a threaded opening 54 for receiving threaded shank 56 of adjusting screw 58. The end of the screw 58 has a knob which can be gripped by the operator and turned to provide axial adjustment of the slide 46.

The left hand end of the slide 46 carries a first pivot member 60 which is secured in upright fashion with respect to the plane of the base of the slide 46. The pivot member 60 has a vertically positioned knife edge 62, which is received within a notch 64 on member 66, the latter being supported on the knife edge and held thereby against axial displacement although free pivoting motion of the pivot member 66 is permitted. The pivoting motion, of course, is effected with respect to a vertical axis corresponding to the knife edge 62.

A cover plate 68 is positioned over the slide 46 to enclose the various pivoting elements of the mechanism.

An adjusting bar is best seen in FIG. 9 at 70. It includes two parts arranged in parallel disposition as shown at 72 and 74. A second pivoted member 76 is carried at the right hand end of the bar parts 72 and 74 as indicated in FIG. 9. Each bar part 72 and 74 is received slidably through openings formed in the element 66. A third pivoted member 77 is supported by an intermediate portion of the parts 72 and 74. These bar parts are received slidably in openings in the member 77.

An end plate 78 is positioned at the left hand end of the bar 70. It is formed with openings through which the bar parts 72 and 74 are slidably received. The bar parts 72 and 74 are joined together by an end piece 80. This piece if formed with a threaded opening 82 which receives a threaded shank 84 of an adjusting screw. A lever 86 is secured to the end of the screw, as indicated best in FIG. 11 and in FIG. 9. This lever 86 extends through a slotted opening 88 formed in the cover plate 68. The end of the threaded portion 84 is secured to the end plate 78, although it is adapted to rotate with respect to the plate 78 by adjusting the lever 86. This position of the anchor member 77 with respect to the anchor member 76 can be changed merely by adjusting the position of the lever 86 in one direction or another.

The various possible adjusted positions for the lever 86 can be indicated by suitable numerical symbols 90 as indicated in FIG. 12. Anchor member 76 engages element 92 having a vV-slot which registers with the knife edge 94 of the pivot member 76. Similarly, element 77 has a knife edge 96 which registers with a V- notch 98 formed in element 100. A threaded rod 102 is received within threaded openings formed in the element 92. The ends of the rod 102 provide an anchor support for strings 104 and 106. The rod 102 may be formed with a slot 108, FIG. 11 through which an adjusting lever extends. The lower end of the adjusting lever 1 10 is secured firmly to the rod 102. When the lever 110 is adjusted, the positions of the string 104 and 106 with respect to the knife edge 94 are changed accordingly. The upper end of the rod 110 extends through a slotted opening 112 in the cover plate 68, as indicated in FIG. 12. Suitable numerical indicia 114 registers the angular position of the lever 110 within the slot 112.

The ends of the strings can be secured to the ends of the rod 102 in the manner illustrated in FIG. 10. The rod 102 is provided with end openings through which the strings 104 and 106 extend. A suitable bead or other form of enlargement is formed on the end of the string, and the string is trained through the opening in the rod 102, from right to left, as viewed in FIG. 10.

The element 92 is secured to temporarily stationary adjusting member 116 which extends in a generally transverse direction, as indicated in FIG. 7. Openings 118 are formed in the adjusting member 116 as indicated in FIG. 11, to permit passage therethrough of the strings and the respective enlargements or beads carried at their ends.

Adjusting member 77 is pivotally supported by element 100. The element 100 in turn is supported by adjusting rod 120. Pivotal element 122 is carried at one end of the rod and pivoted element 124 is carried at the other end thereof. The rod 120 is threaded through openings formed in a transverse direction through the element 100. Secured to the rod 120 is an adjusting lever 128 which extends vertically. A slot 130 formed in the cover plate receives the lever 128. The plate 68 is slotted to accommodate movement of the lever 128. Lever 128 should lie adjusted simultaneously with lever 86.

Pivoted member 124 engages element 132 which is secured to one end of the member 116. Adjusting rod 134 is threadably received through openings formed in the element 132. String 136 is secured to one end of the rod 134 and string 138 is secured to the other end of the rod 134. Pivoted member 122 engages element 140 which is secured to an intermediate portion of the member 116. Both elements 132 and 140 are provided with V-slots that register with knife edges 142 and 144 formed on the pivoted members 124 and 122, respectively. Rod is threadably received through a transverse opening formed in the element 140. The plate 68 is slotted at 152 and 154, respectively, for accommodating the levers 146 and 148.

Adjusting member 116 engages the left-hand end of the adjusting screw 56. The screw 56 may rotate with respect to the adjusting member 116, as it provides an anchor support for the latter. A pilot opening 156 receives one end of the adjusting screw 56. A normally stressed compression spring 158 is situated between the end wall 52 and the adjusting member 116 to maintain the various knife edges in registry when the string tensions are relieved.

The longitudinal position of the adjusting member 116 is registered by an indicator in the form of a rod 160 which extends through one part of the slot 154 in the cover plate 68. Suitable indicia indicating the positions of the adjusting member 116 as well asthe various adjusting levers is provided on each of the slots in the cover plate 68.

' Having thus described a preferred form of my invention, what I claim and desire to secure by US. Letters Patent is:

l. A stringed musical instrument comprising a plurality of musical strings arranged in generally parallel disposition, a means for anchoring one end of each of said strings, a tension adjusting mechanism to which the other ends of each of said strings is connected, said mechanism comprising a common anchor element, manually adjustable means for securing said anchor element and for moving it with respect to said anchoring means, a first adjusting member mounted pivotally on said anchor element in a direction generally transverse to the direction of said strings, pivot elements carried by said first adjusting member, a second adjusting member mounted pivotally at a first location on a 4. The combination set forth in claim 3, wherein said second adjusting member comprises pivot members registering with their associated pivot elements and bars to which the associated ends of said strings are anchored, each bar having connected thereto the ends of a pair of strings, and a pivotal connection between ea hb and its ivot eleme t.

The combihation set forth in claim 4 including anchored, each bar having connected thereto the ends first of said pivot elements, a first pair of said strings being connected at their other ends to said second adjusting member on opposite sides of said first pivot element, and a third adjusting member mounted pivotally on a second of said pivot elements, said third adjusting member carrying third and fourth pivotelements on opposite sides of its pivot point, said third and fourth pivot elements being engaged with said second adjusting member at second and third locations, respectively, a second pair of said strings having their other ends connected to said second adjusting member at said second location and a third pair of said strings having their other ends connected to said second adjusting member at said third location.

2. The combination set forth in claim 13, wherein said third adjusting member comprises: a pivot bar mounted pivotally on said second pivot element, said third and fourth pivot elements being carried by said pivot bar, the separate pairs of said strings being connected to said second adjusting member at said second and third locations whereby the torque produced by the tension in one of said separate pairs of strings connected to said second adjusting member is opposed by the torque due to the tension in the other of said separate pairs of strings connected to said second adjusting member.

3. The combination as set forth in claim 2, wherein said first, second and third locations on said second adjusting member are spaced transversely with respect to the direction in which said strings are situated.

of a pair of strings, and a pivotal connection between each bar and its pivot element.

7. The combination set forth in claim 6 including manually adjusting means for changing the position of each of said bars in a direction transverse to the direction of said strings relative to its associated pivot element whereby the relative tensions of the strings of each of said pairs can be varied.

8. The combination as set forth in claim 1, wherein said first, second and third locations on said second adjusting member are spaced transversely with respect to the direction in which said strings are situated.

9. The combination set forth in claim 8, wherein said second adjusting member comprises pivot members registering with their associated pivot elements and bars to which the associated ends of said strings are anchored, each bar having connected thereto the ends of a pair of strings, and a pivotal connection between each bar and its pivot element.

10. The combination set forth in claim 9 including manually adjusting means for changing the position of each of said bars in a direction transverse to the direction of said strings relative to its associated pivot element whereby the relative tensions of the strings of each of said pairs can be varied.

11. The combination set forth in claim 1, wherein said second adjusting member comprises pivot members registering with their associated pivot elements and bars to which the associated ends of said strings are anchored, each bar having connected thereto the ends of a pair of strings, and a pivotal connection between each bar and its pivot element.

12. The combination set forth in claim 11 including manually adjusting means for changing the position of each of said bars in a direction transverse to the direction of said strings relative to its associated pivot element whereby the relative tensions of the strings of each of said pairs can be varied.

3 3 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,695,137 Dated October 3, 1972 lnve fisi Robert C. Enrich It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

i ClairnZ, line 1, "claim 13" should be --clain1 l--. Claim 3, line I, .1 claim 2" should be -claim 1--. Claim 8, line 1, claim l"-should be Signed and sealed this 13th day of February 1973..

(SEAL) Attest:

EDWARD I I. FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents zg gg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 695, 137 Dar- Gotober 3Q 1972 InventorCfizl Robert C, E'urich It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

F- Claim 2, line l, "claim 13" should be -clain1 1--. Claim 3, line 1,

"claim 2" should be -claim 1-. Claim 8, line 1, "claim 1" should be --clairn 2.

Signed and sealed this 13th day of February 1973.

(SEAL) Attest:

EDWARD l l. FLI'ITCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

1. A stringed musical instrument comprising a plurality of musical strings arranged in generally parallel disposition, a means for anchoring one end of each of said strings, a tension adjusting mechanism to which the other ends of each of said strings is connected, said mechanism comprising a common anchor element, manually adjustable means for securing said anchor element and for moving it with respect to said anchoring means, a first adjusting member mounted pivotally on said anchor element in a direction generally transverse to the direction of said strings, pivot elements carried by said first adjusting member, a second adjusting member mounted pivotally at a first location on a first of said pivot elements, a first pair of said strings being connected at their other ends to said second adjusting member on opposite sides of said first pivot element, and a third adjusting member mounted pivotally on a second of said pivot elements, said third adjusting member carrying third and fourth pivot elements on opposite sides of its pivot point, said third and fourth pivot elements being engaged with said second adjusting member at second and third locations, respectively, a second pair of said stringS having their other ends connected to said second adjusting member at said second location and a third pair of said strings having their other ends connected to said second adjusting member at said third location.
 2. The combination set forth in claim 13, wherein said third adjusting member comprises: a pivot bar mounted pivotally on said second pivot element, said third and fourth pivot elements being carried by said pivot bar, the separate pairs of said strings being connected to said second adjusting member at said second and third locations whereby the torque produced by the tension in one of said separate pairs of strings connected to said second adjusting member is opposed by the torque due to the tension in the other of said separate pairs of strings connected to said second adjusting member.
 3. The combination as set forth in claim 2, wherein said first, second and third locations on said second adjusting member are spaced transversely with respect to the direction in which said strings are situated.
 4. The combination set forth in claim 3, wherein said second adjusting member comprises pivot members registering with their associated pivot elements and bars to which the associated ends of said strings are anchored, each bar having connected thereto the ends of a pair of strings, and a pivotal connection between each bar and its pivot element.
 5. The combination set forth in claim 4 including manually adjusting means for changing the position of each of said bars in a direction transverse to the direction of said strings relative to its associated pivot element whereby the relative tensions of the strings of each of said pairs can be varied.
 6. The combination set forth in claim 2, wherein said second adjusting member comprises pivot members registering with their associated pivot elements and bars to which the associated ends of said strings are anchored, each bar having connected thereto the ends of a pair of strings, and a pivotal connection between each bar and its pivot element.
 7. The combination set forth in claim 6 including manually adjusting means for changing the position of each of said bars in a direction transverse to the direction of said strings relative to its associated pivot element whereby the relative tensions of the strings of each of said pairs can be varied.
 8. The combination as set forth in claim 1, wherein said first, second and third locations on said second adjusting member are spaced transversely with respect to the direction in which said strings are situated.
 9. The combination set forth in claim 8, wherein said second adjusting member comprises pivot members registering with their associated pivot elements and bars to which the associated ends of said strings are anchored, each bar having connected thereto the ends of a pair of strings, and a pivotal connection between each bar and its pivot element.
 10. The combination set forth in claim 9 including manually adjusting means for changing the position of each of said bars in a direction transverse to the direction of said strings relative to its associated pivot element whereby the relative tensions of the strings of each of said pairs can be varied.
 11. The combination set forth in claim 1, wherein said second adjusting member comprises pivot members registering with their associated pivot elements and bars to which the associated ends of said strings are anchored, each bar having connected thereto the ends of a pair of strings, and a pivotal connection between each bar and its pivot element.
 12. The combination set forth in claim 11 including manually adjusting means for changing the position of each of said bars in a direction transverse to the direction of said strings relative to its associated pivot element whereby the relative tensions of the strings of each of said pairs can be varied. 